I am newbie in OpenLDAP. Prersently I am running an OpenLDAP as the
authentication of Postfix+IMAP email server.
How can I take backup and maintain the database of LDAP ? what are the
commands ?
I like to place the associated commands in a cron jobs.
Please enlighten me. thanks

slapcat is the command for you.
Also be sure you don't let bdb transaction logs take over your hdd.
(see db_archive or options in DB_CONFIG)